Simple offset cutting with Qcad-Cam

Using my Qcad-cam config file simple offset cutting of closed contours can be  made to quickly produce parts.

To use the normal or climb cut options, 3 settings as well as the Z level can be set in the Qcad layer name. The reversed  direction of a closed contour inside another will be automatic keeping the same offset setting.

Firstly ‘NC’ or ‘CC’ followed by the tool diameter for the offset. Normal cut is counter clock wise on the outer with a G42 code , cut to the right offset. Climb cut is  clock wise on the outer with a G41 code , cut left to the line. Forced orientation in the CAM Configuration  must be set to “Undefined”.

‘RD’  followed by a value is the ramp arc diameter for entering and exiting the cut. This over rides the ramp in length set in the CAM dialog.

‘RS’ is the sweep in degrees also for  entering and exiting the cut, the default is 180 degrees .

A layer name would look like the following with Z cutting set to -2.4 –


Using tool Diameter Offset Cutting with my QCAD- CAM config file.

Any CNC machine will offer cutter compensation by moving along the left or the right of the path by using the G41 or G42 command.

My config file has two options to insert these commands.

  • Add ‘G41′ or ’42’ followed by the diameter of the cutter in the layer name or custom property’s editor. This is the only method to be used for open contours.
  • CC (climb cut) – NC (normal cut) these also have the tool diameter value for offset cutting in the layer name or custom property’s editor, the cut direction will be set automatically. Closed contours inside each other will have their direction reversed.

Setting the cut direction of Contours with My Qcad CAM config file.

Open contours

Standard Qcad-Cam will always cut from the nearest end from  the last cut. Using my file his can now  be overridden by selecting the desired first entity and setting  ‘Start’  with the Custom Property Editor in the main CAD file. You must always be certain of the direction of open contours when using G41-G42.

Closed contours

The cut direction of closed contours can be set by the following.

  • cw

    Cut direction set in layer names.

    First of all is the standard Qcad-Cam dialog. This is the only method allowed  in the basic Gcode.js config.

  • CW or AW(anti-clock-wise) set in the layer name or the Custom Property Editor.
  • CC (climb cut) – NC (normal cut) these also have the tool diameter value for offset

    Cut direction

    cutting, the cut direction will be set automatically. Closed contours inside each other will have their direction reversed. This is the most useful option for when  cutting parts.

Setting the Z level using my QCad CAM config file

Using layer and custom property’s Is a easy way to configure your CAM in QCad. In my config file upper case letters are used sometimes followed with a value.

Here is a QCad and Linuxcnc screen showing how the Z level can be set.

The Z level for the first cut is with a ‘Z’ and number value in the layer name.  The second cut is assigned to the variable name and set with a Z value all in the same layer name. A different layer can use that same variable ‘#1’. This cut level can be quickly changed latter at the beginning of the Gcode file.

Screen Shoot

Screen Sho

If no Z levels where assigned then the default “cut” variable would be used. Values for Cut, Safety and Clear variables are set from the Qcad CAM dialog and can also be quickly changed later when using the Gcode file.

Z levels can also be set using the entity Property Editor by assigning a ‘Z’ custom property. This will have priority over the above layer name method.

Feed rates can also be changed by using ‘F(rate)’.

Qcad GCode configuration File v.41

It took a lot of hours working it out but its now done.

Years ago I had a look at C and C++ and at last it has come to some use with this java-script file . If you don’t have your head around object orientated programming then don’t go any further than the write-header and write-footer functions.

Features  set by layer name or entity custom attributes  include-

  • Z level with or without variable.
  • Normal cut or Climb cut.
  • User defined rapids.
  • Set start point for closed or open contours.
  • Set direction for closed contours.
  • Tool diameter compensation.

It has everything I need to cut my products and some more.

The full version is  available in my store for a small app fee here. 

now up to v.41

QCad LinuxCNC Gcode Config File

When trying to develop a hobby business with little capital it means that you have to learn a lot of stuff. You use stuff that you like and is free.

The main Qcad 2D CAD program is open source and runs on Linux as well as Windows and this is what I use for  the drafting  of all aircraft on this site.

It comes with a CAM add-on trial to output GCode which I then use with LinuxCNC.

The CAM add-on in QCad-CAM professional  uses a configuration file which can be modified to suit the users needs. So far file below best suits my needs and will not meet all of anyone else’s. So please use, modify and test in a simulator first.


Warning this file is experimental !!

GCodesrl Right click and save as. Ver .1